Spark-plug.



J. H. GRAHAM. SPARK PLUG. APPLICATION FILED MAY 6, 1915.

Patented 00t.1( ),'1916.

.7 i If v lmm Fi i Fig. 1.

Fi i.

Fig 41. Fi s.

ATTO NE PATENT OFFIGE.

JAMES H. GRAHAM, F TOBRINGTON, CONNECTICUT, ASSIGNOR T0 SPLITDORF ELECTRICAL COMPANY, OF NEWARK, NEW JERSEY.

' SPARK-PLUG.

Specification of Letters Patent.

Patented Oct. 10, 1916.

v To all whom it may concern Be it known that I, James H. GRAHAM, a citizen of the United States, residing at Torrington, in the county of Litchfield and State of Connecticut, have invented certain new and useful Improvements in Spark- Plugs, of which the following is a specifia spark plug such as used for igniting charges in internal combustion engines.

One of tlie'objects of my invention is to provide a spark plug, the parts of which when assembled will retain their relative position when subjected to the heat of the engine cylinders.

In some types of internal combustion engines, the cylinders get much hotter than in others, owing to the differences in the cooling system, construction of the engine cylinders and the manner of placing the spark plugs.

In the usual form of spark plug, the main ,insulator for the center electrode is held in position by means of a stufling nut engaging the body or, shell of the plug and drawing downward on the insulator against suitable I gaskets; I have found in practice that in this type of construction, due to the expansion ofthe parts from the heat derived fromthe engine cylinders, the parts become loosened and misplaced by the vibration of the engine to such an extent that the spark plug is rendered useless.

My invention is directed to means for correcting these faults, at the same time keeping the number of parts reduced to aminimum and thereby providing a plug which is cheap to manufacture and easy to assemble.

One embodiment of my invention is shown in the drawing, wherein Figure 1 is an assembled view of my improved spark plug; Fig. 2 is a sectional view of Fig. 1 ,Fig. 3 is an assembled view of the center-electrode, main insulator and stuffing nut; 'Fig.'4.- is a plan view of the locking deyice used in the assembly of my plug; Fig. 5 is a side elevation of Fig. 4.

Referring now particularly to the details 3 illustrates one form of a ground electrode. The center electrode 1 is covered by an insulator 7 made of mica or other suitable material. One end of the electrode 4 has threads 18 and at the opposite end is shown an electrode point 5, securely'fastened in the recess 6 of the electrode. The point 5 may be of special material or it can be integral with the main part of the electrode 4c.

8 is a stuffing nut or gland having a chamfered part 21 and threads 19 at one end.

In the form shown, the center electrode is tapered from the threaded part to a point 22 near the opposite end. As the mica is wound onto the electrode, it bulges slightly at the point 22 therebyfurnishing a pinching point for the stufling nut or gland 8 which is tapered internally to correspond to the taper on the center electrode 4, the mica being put on substantially uniform in thickness. Fig.

3 shows the insulator 7 and stuiiing nut or 4 before they are put into the plug, thereby forming a unitary structure of these parts.

The upper portion of the shell 1 is contracted or shouldered at, 21 in a suitable manner to receive a gasket 9 of any well known type which is first dropped into place when the plug is to be assembled and then the integral structure just described and shown in Fig. 3 is passed through the shell of the plug and a locking device, shown as a lock washer 10 is then put into position over the top of the electrode 4 and insulator 7. The lock nut 11 is then put into position and turned as tightly as possible.

The locking devlce 10 is preferably made of steel and given a spring temper and has an openin 20 between the limbs whichare oil'set as s own in Fig. 5"so that when the locking nut .11 is drawn up, the limbs of the locking device 10 engage the shell 1 and the locking nut 11, in such a manner as to take up any expansion there may be between -."tion, thereby putting a constant strain on the tapered electrode which insures a tight fit with the stufiing nut or gland 8.

It will be noted that the nut 18 is adapted to take a particular form of terminal, yet it will be understood that any type of nut or nuts may be used to receive the various styles of terminals. After the assembly of the plug .has been completed in the manner as outlined above, the ground electrode 3 is then put into place.

While I have shown my invention applied to one particular form of plug, it will be apparent to anyone skilled in the art that numerous changes and alterations may be made without departing from the spirit of the invention or the scope of the appended claims.

Having thus described my invention, what.

I claim is 1. In a spark plug, the combination of a shell having a central hole contracted at the top, a gasket adapted to lie within the contracted portion, a central electrode and an insulator therefor, a stuiiing' gland adapted to engage said insulator and said gasket, a locking nut adapted to engage the end of said stufiing gland and a locking device between said shell and said locking nut.

2. In a spark plug, the combination of a I shell having a central hole contracted at the top, a gasket adapted to lie within the contracted portion, a central electrode having an insulator and a stuiiing gland mounted thereon as a unitary structure, said gland being threaded and chamfered at one end to receive a locking nut and to engage said gasket and a locking device between said lock nut and said shell.

3. In a spark plug, the combination of a shell having a central bore of substantiallyuniform diameter but'having a shoulder at one end of said bore, a gasket adapted to engage said shoulder, a central electrode, a main insulator for said electrode, a 'stufiing gland fastened to said insulator and adapted to hold said insulator and electrode within the shell, a locking nut for said gland .to draw the insulator, electrode and gland into Working relation with the shell and a locking device between the lock nut and the shell.

4. In a spark plug, the combination of a shell having a bore with an inner shoulder at one end, a gasket to engage said shoulder, a center electrode having a sparking point at one end and threaded at the other and being tapered between .the ends, insulating material mounted on the tapered part of said electrode, a stuffing land internally tapered to correspond With he taper on said electrode and mounted on the insulating material, said gland being externally threaded atone end and chamfered below the threaded portion to engage said gasket, a locking nut to engage the threaded part of said gland and a locking device between said lock nut and the shell.

5. In a spark plug, the combination of a shell having a central bore with an inner shoulder at one end, a gasket adapted to engage said shoulder, a unitary electrode structure, consisting of a metallic center, carrying a sparking point, an insulator and a stuffing gland, said unitary structure adapted to go within said shell, a locking nut outside said shell to engage the stuffing gland to hold the unitary electrode structure in working position against said gasket in the.

shell and a locking device between the lock nut and the shell for the purpose described.

6. In a spark plug, the combination of a shell having a central bore contracted at one end, a gasket adapted to fit within the contracted part, a tapered central electrode 7. In a spark plug, the combination of shell having a central bore contracted at one end, a gasket adapted to fit within the contracted part, a-tapered central electrode threaded at one end and havlng a sparking point at the other, an insulator mounted on.

the electrode, a stufling gland mounted on the insulator, a lock nut outside the shell and adapted to engage the stufling nut to draw the same against said gasket, a looking device between the lock nut and the shell,

a cupped washer above the lock nut, a gasket within sa1d cupped washer, a secondary insulator resting on sa1d second mentloned gasket and within the cupped Washer and means for locking sa1d secondary insulator to the shell of the plug, and means for putting a constant tension between the center electrode and the stuliing gland.

8. In a spark plug, the combination of a shell having'a central bore contracted at one to hold said parts in Working position in end, a gasket adapted to fit within the son the shell and a locking device between said tracted part, a central electrode and an infastening means and said shell. 10 sulator therefor, means for supporting said In testimony whereof, I atfix my signa- 5 electi ede and insulator Within said shell, said ture.

means extending outside said shell and adapted to be engaged by fastening means JAMES H. GRAHAM. 

